1. CHAPTER 8: SEDIMENTARY ROCK

2. Sedimentary rock is formed from the weathered and eroded remains of other rocks
Many of the rock layers in this photograph are composed of sediments that accumulated on the seafloor.
What evidence would reveal to a geologist that a rock formed in a marine environment?

3. Sedimentary Rock
Most of Earth’s surface is covered with layers of loose sediment
>75% of the land surface is Sedimentary Rock

4. Why study sedimentary rocks?
Fossiliferous Cambrian Burgess Shale at Mt. Stephen, BC
They reflect physical and chemical characteristics of their source environments and depositional processes
They contain direct and indirect evidence of life and its evolution
They can be interpreted to understand geological history
The are the source of important resources, including metals, building materials and energy
Planetary nebula remaining mineral particles and gas after a star explodes
Steven Earle
Triassic limestone being quarried for cement at Texada Island, BC
Steven Earle

5. There are three common types of sediment: Clastic, Chemical, and Biogenic
CLASTIC SEDIMENTS are broken and eroded pieces of rocks and minerals
deposited by water, wind, ice, or some other physical process
What is the main mineral in this sandy sediment?
What else might be present?

6. Chemical and Biogenic Sediments
CHEMICAL SEDIMENTS are produced by inorganic (nonbiological) precipitation of dissolved compounds (e.g., through evaporation)
BIOGENIC SEDIMENTS are produced by organic (biological) precipitation of the remains of living organisms
Comet exhibiting coma (tail)

7. Change in Sediments
Sediments change as they are transported across Earth’s surface… en route to their depositional environment
What are the likely depositional environments of these three types of sediment?

8. Particle Size Reflects Depositional Energy

9. Sorting
Particles separated based on grain size

10. Decreasing grain size with increased transport distance and decreased energy level
Suggested tips to give students: During World War II, geologists employed by the military carried out studies of the sea floor, mapping deep-sea trenches. The purpose of the study was to discern possible hiding places for enemy and Allied Forces submarines.

11. ? Coral Pink Sand Dunes, southern Utah
Steven Earle
What does multi-generational mean in this context? Why are these grains so well rounded and so dominated by quartz?
0.1 mm
Close-up view of the multi-generational fine-grained sand at the Coral Pink Sand Dunes
Steven Earle

12. Clastic Grains
Clastic grains combine with chemical and biogenic sediments through either organic or inorganic precipitation.
The black material in these thin sections photographs is organic matter.

13. Sedimentary Basins
Dissolved compounds are transported from weathering sites into Sedimentary Basins

14. Sediments evolve during transportation and deposition.
Unstable grains (olivine, pyroxene, feldspar, amphibole, and others) become less abundant
Stable grains (quartz, clays, muscovite) become more abundant
Biogenic sediments accumulate
Chemical sediments may become more abundant

15. The Sedimentary Cycle
Sediment becomes sedimentary rock during the sedimentary cycle
Sediments typically accumulate at rates of less than 1 mm per year. How long would it take to accumulate 1000 m of sediment at a rate of 0.2 mm/year?
Suggested tips to give students: is an animation showing localities around the Ring of Fire. People who live around the Ring of Fire are in continuous danger from earthquakes and volcanic activity.

16. Lithification
Lithification is caused by compaction and cementation

17. The important types of clastic sedimentary rock
Distinguished by:
grain size and shape
grain type (mineralogy)
texture of the grains, matrix and cements
Why are they called clastic sedimentary rocks? What is a clast?

18. Types of Sediment
Specific combinations of texture and composition for each type.
Determined by sediment’s history: transport energy and distance, weathering intensity, and composition of source rock.

19. Important clastic sedimentary rocks
conglomerate breccia quartz sandstone arkose
What is the textural difference between conglomerate and breccia?
What are the compositional differences between quartz sandstone, arkose and lithic sandstone?
lithic sandstone siltstone claystone shale

20. Chemical sedimentary rocks
Rock salt
Gyspum
Chert
Travertine

21. Biogenic Sedimentary Rock
Skeletal
limestone
Chalk
Coal
What do skeletal limestone, chalk and coquina have in common?
Coquina

22. Sedimentary rocks preserve evidence of past environments and ecology

23. Continental depositional environments
Wetland, alluvial fan, stream, desert, lake, glacier – which is which?
Do all of these environments exist in Canada?

24. Coastal depositional environments
Barrier island, carbonate lagoon, beach, tidal wetland, delta – which is which? Do all of these environments exist in Canada?

25. Marine Environments of deposition

26. Primary sedimentary structures record modern and ancient sedimentary processes
Ripples
Mud Cracks

27. Cross-bedding in eolian sandstones, Zion Canyon, Utah
Steven Earle
Graded bedding in submarine fan rocks, Gabriola Island ,BC
Steven Earle
Bedding in fluvial and lacustrine deposits, Horseshoe Canyon, Alberta

28. Choose four depositional environments in this figure
Choose four depositional environments in this figure. For each, describe the texture of the sediments likely to form there.
Consider the beach and glacier. If the sediment source for each was granitic mountains, predict the composition of sediments in each case.
Haiti, 2010

29. COPYRIGHT
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